Lower Serpukhovian carbonate psephitolites in the central part of the Chernyshev ridge

The paper presents the results of the study of carbonate psephitolites developed in the Lower Serpukhovian deposits in the Central part of the Chernyshev Ridge. They have different morphology and genesis. There include sedimentation breccia and post-sedimentation intra-formation units, however thick strata of brecciated rocks have the most problematic genesis indicating the formation of these clastic carbonate rocks during sedimentation and post-sedimentation processes. As a result we determined that a shallow sea basin existed on the territory of the central part of the Chernyshev Ridge in the Early Serpukhovian period. In the western part, shallow sediments, including intraplate karst breccias and coastal-marine detrital limestones, were deposited in shoals with island uplifts and lagoons. At the same time, dark-colored limestone silts were accumulated in the deeper sea in the east, and intercalated with removed debritic flows. During the Ural orogeny, due to the layer-by-layer breakdown at the base of the Serpukhovian, thick strata of intensively breccated carbonate deposits were formed. Post-sedimentation processes of changes in the Lower Serpukhovian sediments (recrystallization, dolomitization, partial dissolution) could occur during major Middle and Upper Carboniferous regressions, as well as after the change of the elysial hydrogeological regime to infiltration at the Triassic-Jurassic boundary. They have continued up to the present time. This is especially evident in the eastern part of this territory in areas of increased permeability of rocks. There are intensive processes of leaching, dolomitization, calcitization, and karst developing.